(a) Field of the Invention
The present invention relates to liquid crystal display device (“LCD”) and a method of manufacturing the same. More particularly, the present invention relates to a method of manufacturing an LCD using an ion beam alignment method.
(b) Description of the Related Art
A liquid crystal display (“LCD”) is one of the most popular display devices. A typical LCD includes two display panels each having a substrate with a field generating electrode, and a liquid crystal layer interposed between the two display panels. The LCD controls an amount of light transmitted therethrough by controlling the alignment of liquid crystal molecules of the liquid crystal layer by applying a voltage to the field generating electrodes.
Although the LCD has a drawback of a narrow viewing angle due to the optical anisotropy of liquid crystal molecules, an optically compensated bend (“OCB”) mode, an in-plane switching (“IPS”) mode, and various vertical alignment modes using a plurality of domains have been introduced to realize a wide viewing angle. The plurality of domains may be formed by artificially distorting the electric field.
In order to form the plurality of domains, a protrusion or a cutout has been formed on the field generating electrode. In this method of domain formation the plurality of domains are formed by aligning liquid crystal molecules vertically to a flange field by the flange field that is formed between an edge of the protrusion or the cutout and a field generating electrode facing the edge. However, a process of forming the protrusion or the cutout is very complicated, and it increases the manufacturing cost of a display device. Also, the aperture ratio of the LCD is reduced. Further, a random motion is generated at liquid crystal molecules located at the center of a pixel, far away from the cutout, even though liquid crystal molecules adjacent to the protrusion or the cutout are easily aligned vertically to the flange field. Therefore, response speed is decreased, and an afterimage may be generated due to a reverse-direction domain.
As another method for forming a plurality of domains in one pixel, a photo-alignment method and an ion beam alignment method have been introduced. In the photo-alignment method and the ion beam alignment method, an alignment direction and an alignment angle of liquid crystal molecules are controlled by radiating light or ions to an alignment layer. Therefore, it is possible to increase the aperture ratio because it is not necessary to form a protrusion or a cutout on a field generating electrode in the photo-alignment method and the ion beam alignment method. It is also possible to improve the response time of liquid crystal molecules due to a pretilt angle that is generated when photo-alignment or ion beam alignment is performed. Furthermore, if a protrusion or cutout is additionally formed after performing the ion beam alignment, the response time of the liquid crystal may be further improved because friction defects caused by rubbing alignment, another form of alignment layer formation, are prevented and defects are not generated even though the liquid crystal molecules are not completely aligned.